Electrosurgery requires controlled application, with an instrument, of radio frequency energy to an operative tissue site. To achieve successful clinical results during surgery, the electrosurgical generator, as the source of the high frequency or radio frequency energy, should be mated correctly with an appropriate instrument for a specific surgery. Due to the variety of operative electrosurgical procedures requiring various levels of radio frequency energy delivery from an attached instrument, problems arise with mismatching an electrosurgical generator and the instrument. The operating rooms with a variety of instruments and generators available for surgery create a potential for mismatch problems and thus may increase the patient risk.
U.S. Pat. No. 5,400,267 discloses a system with a non volatile memory with an EEPROM in the instrument or its attached cable. The memory identifies the instrument. A problem arises when the memory is located external to the power supply requiring hardwire connections. The communicated data transmission from the memory to the control may have an error due to radiated emissions from radio frequency energy wires located closely when delivered by the electrosurgical generator during surgery. Radio frequency exposure will interfere with the identification information being transmitted so it becomes difficult to determine that the correct medical instrument is attached to the power source. In addition a further problem is presented because the memory means must be located in the reusable part of the medical instrument. For purposes of instrument identification, this patent restricts application to reusable medical instruments and prohibits an instrument identification for low cost disposables.
U.S. Pat. No. 5,413,573 describes identification of surgical instruments by incorporating a unique interface between two components such that their engagement by two surfaces defines the identity of an instrument if properly mated. In this system, a switch is provided on a component first surface called the orientation means. A second surface incorporates a contact on an intermediate component. Upon engagement of these two components the appropriate switch and contact mating establish the given identity. A problem arises with this approach, as the integrity of the identity depends on the engagement with the mating of components. A degradation of this identification occurs, with repeated engagements causing deterioration of the mating switch to contact interface between components. A secondary problem also occurs from the multiple engagement process as this approach requires a specific orientation alignment between mating surfaces. As the numbers of switch to contact interfaces increase, a tighter tolerance must be maintained between mating surfaces to retrieve the identity information. Repeated component engagements will also deteriorate this orientation alignment and thus degrade the accuracy in maintaining the identity.
U.S. Pat. No. 5,434,398 uses a magnetic encoding process to establish the identity with a card based system. Modulated magnetic fields embedded in a smart card require the use of a ferromagnetic element to retain the unique identity code. A magnetic reader decodes the card information allowing system activation. Exposure of this system to radio frequency energy used in electrosurgery, could effect the integrity of the magnetic smart card and degrade the ability of the magnetic based card reader to accurately decode its proper identity. Radio frequency energy would remagnetize both the smart card and reader by induced magnetic coupling to the ferromagnetic elements. Clearly this system would require magnetic shielding to retain identity data. Indeterminate magnetic sources present in the operating room also creates additional major problems for this system and would make its use in electrosurgery suspect.
U.S. Pat. No. 5,396,062 describes a power source receptacle system with detection of the presence of a mated plug, by using an optical coupling technique, established by beam passage through the receptacle. This approach uses a light emitter to generate a beam, that passes through openings in the receptacle contacts, to a receiver aligned on a dedicated optical axis. A powered instrument having a bladed plug for insertion in a receptacle breaks the beam transmission path sending a corresponding signal to a controller that detects the plug engagement. The '062 patent is limited in use, in that, it provides for detection when a mating plug is either inserted or removed from the receptacle. Power can only be activated or deactivated in the receptacle, based on whether the mating plug is engaged or disengaged. Numerous problems are presented by this system. First, the identity is not recognized or associated to a given instrument plugged into the receptacle. Second, the power applied to the receptacle cannot be differentiated between specific pluggable instruments. Also, additional problems are presented, because a specific optical axial alignment is required for beam passage, through the openings in the power receptacle contacts, thereby requiring a specific mechanical alignment integrity. U.S. Pat. No. 5,625,370 has an electromagnetic device and method in an identification system apparatus. An electrically conductive material is disposed to pass through a magnetic flux loop of the electromagnetic device. The coupling established between those components is the means by which identification information is transferred. An antenna may also be electrically connected to the conductive material to augment the apparatus for receiving transmitted identification information. Multiple identification problems exist with radio frequency based equipment due to radiation coupling with the electromagnetic conductive strip and antenna which will deteriorate the identity signals. Error borne signals lose their identity and become inaccurate with decoding. The radio frequency energy may also electromagnetically couple to distort the magnetic flux loop of the electromagnetic device. This will reduce the signal to noise ratio during information transfer and lower the accuracy of the identity information recovered.
International Patent WO9608794 has a security code identification circuit that uses a radio frequency based card reader and decoder method to recover a digital security code. The card reader includes a receiving antenna sensitive to a signal generated to an access card. A receiver circuit is coupled to the receiving antenna to detect and process an analog signal that is then converted to a digital security code. A problem with this type of recognition system makes it error borne and unacceptable for code identification in radio frequency systems. Radio frequency energy contains components that will be picked up and coupled by the reader receiving antenna as it is sensitive to those frequencies. This will confuse the card reader antenna and detector electronics. Erroneous signal components will be processed along with the identification signal; thus, generating errors in the detected signal. The recognition system digital security code could not be a true representation of the signal information and thus identification is inaccurate for use with radio frequency based equipment.
U.S. Pat. No. 5,660,567 has a smart connector for a sensor with removable encoding medical device. The smart identification method is accomplished within the connector module pin interconnect wherein a dedicated group of removable pins from a multiple pin connector are used to attach an encoding device read by the sourcing equipment. The sensor, attached to this connector with encoding device, identifies the medical device. The smart connector distinguishes either a resistor, an electronic device, a memory device or a modulating device to identify the medical device. Insertion and removal of an encoder requires assembly, thereby making the accuracy and repeatability of the identification process suspect and prone to error. Recovery of the smart signal interface is dependent on the reliability of the electrical and mechanical connections required as mechanical misregistration and intermittent electrical contacts will degrade accuracy. In applications where radio frequency energy exists proximate to the encoding, the corruption of electronic signals used for identity recognition will result. Radio frequency energy will radiate and conductively couple with electronic or memory devices to reduce the accuracy of decoded signals.
U.S. Pat. No. 5,651,780 has an identification and monitoring method for recognizing the physical and or functional characteristics of medical devices. Identification means located within the medical instrument uses an electronic memory such as a non-volatile RAM, ROM, EEPROM or EPROM. Information is stored about the medical device attributes in look-up tables within a power source include an acceptable device list or performance characteristic to compare to the attached instrument to determine application use. The identification teachings of this patent are similar to the one identified in U.S. Pat. No. 5,400,267. The problems with '780 are similar to those mentioned for the '267 patent.
A solution to the above problems is disclosed and claimed herein and it addresses the noted limitations of the patents discussed. A smart recognition system for electrosurgery includes a smart connector sensing topology. In addition to uniquely recognizing the correct mating of electrosurgical power sources with the attached pluggable medical instruments the smart connector sensing approach herein provides a solution that has inherent immunity to the problems discussed. The present system has the smart identification code integral to the connector assembly to avoid assembly errors. Use of a non-contact, optical method smart signal recovery eliminates electrical contact degradation and mechanical misalignment problems. An infrared diffuse reflectance code identification recovery method which has inherent accuracy and reliability in harsh, high power radio frequency electrosurgical environments and application in fields outside electrosurgery.